Ac unit is not working properly just replaced the compressor the dryer and the orfice and it blows cold one minute and then the unit gets hot and dies the motor down.. What could be causing this? the unit is not over pressurized it has been checked

A system will only drop temp about 20 degrees from outside temp. I would have then recheck the Freon level again. To much is as bad as to little when it come to Freon. Also the oil level can be to high causing the same thing. When they changed the compressor they should have also replaced the dryer and the orfice tube/screen. If that wasn't don't you could have a obstruction in line.

did the check or change the expension valve,and also check the dryer and may be it need oil in the compressor when it has load it may run hot,another thing to check make sure the car cooling fans work properly

My 2003 Toyota Camry AC often starts blowing hot air and the AC light starts blinking. I don't know why the following process works, but it does. Using the temp selector (left) reduce the temperature all the way down to Max Cold and then push the Auto button. It will start blowing out very cold air. After a little while push the temp selector to the desired temperature.

If the car was retro fitted with R134a this was a common problem. There was a low side pressure sensor that needs to be changed. R134a runs different pressures than the r12.. When you go down the road the condenser cools off the system and the pressure drops below the minimum pressure. You need to make sure that the system is fully charged, not just cold to the feel. Both pipes coming out of the firewall need to be the same temp. this makes sure that the evaporator is flooded.
I hope this helped. Re-post if you need more info. Have a nice day and good luck.

you have moisture in the system this causes your expancion valve to freeze up an stop working, thats why it works for sort time and when it de-freezes stars working again. you need to do a EVAC & RECHARGE with a good AC service equipment, specially attention to pull vacumm por at least 20minutes so you get all moisture out of the system.
Good luck

Did you change the Receiver/ Drier and the Orfice Tube/ Expansion Valve? The Receiver/ Drier takes moisture out of the system and the Orfice Tube/ Expansion Valve controls the Hot/ Cold air. If that is bad it may not be opening or closing fully which would not let your A/C get as cool as it supposed to.

I believe there is a expansion valve located on the back part of the air conditioner on the back right side i believe that could be the problem. I think if I am understanding you correctly, your back air is not as cool as it should be or not cold at all. Might want to check this. If I am not understanding you correctly please let me know again what your problem is.

no dealer has a reset for the a/c system by you mentioning that you replace everything it means the a/c compressor,air dryer,and the most important the orfice tube. if you hadnt replace the orfice tube wich converts the liquid into gas when it gets hot thats your problem.alot of mechanics wont change it as an a/c mechanic will.

orfice tube stoped up or make shure motor electric fan comes on when u cut ur ac on with motor runing

check the dryer maybe its blocked